1. Field of the Invention
The invention relates to lubricating oil compositions. It more particularly relates to lubricating oil compositions that have the ability not only to lubricate an engine, but also to reduce the amount of fuel consumed by such engine. Even more particularly it relates to lubricants containing a small amount of a hydroxyl-containing acid ester.
2. Discussion of the Prior Art
For several years there have been numerous efforts to reduce the amount of fuel consumed by automobile engines and the like. The search for ways to do this was given added impetus by the oil embargo. Many of the solutions have been strictly mechanical, as for example, setting the engine for a leaner burn or simply building smaller cars and smaller engines.
Other efforts have revolved around finding lubricants that reduce the overall friction in the engine, thus allowing a reduction in energy requirements thereto. A considerable amount of work has been done with mineral lubricating oils and greases, modifying them with additives to enhance their friction properties. On the other hand, new lubricants have been synthesized and compounded for use in modern engines. Among these is Mobil 1, a synthetic hydrocarbon fluid and synthetic ester blend, which is known to reduce fuel consumption by a significant amount. With respect to the present Mobil 1 formulation, it is, however, the physical properties of the oil itself that provide improved lubricating (and thus improved fuel consumption) and not the additives therein.
So far as is known, no effort has been made to employ single hydroxyl-containing acid esters at the concentrations necessary for the present invention. U.S. Pat. No. 2,788,326 discloses some of the esters suitable for the present invention, e.g. glycerol monooleate, as components of lubricating oil compositions. However, in each case they are in conjunction with other similar esters. It should be noted that 1% glycerol monooleate gave little advantage as shown in the table in column 7. U.S. Pat. No. 3,235,498 discloses, among others, the same ester as just mentioned. But the patent teaches the use of 0.001 to 1.0% of such esters. Such low percentages do not operate to give the advantages of the present invention.